Electrosurgical forceps are known that employ mechanical clamping action and electrical energy to cut, cauterize, coagulate, desiccate, and/or reduce bleeding in living tissue during surgical procedures. Conventional electrosurgical forceps typically have a pair of opposing jaw members, each forming an electrode charged to a different electrical potential. The pair of opposing jaw members are configured to grasp the living tissue, and to transfer bipolar energy through the living tissue, allowing a surgeon to effect hemostatis and/or tissue-cutting actions at least in part by controlling the intensity, frequency, and/or duration of the bipolar energy applied between the respective electrodes and through the tissue.
In a typical mode of operation of such conventional electrosurgical forceps, the transfer of bipolar energy through the living tissue initially causes an electrical current to flow through the tissue generally perpendicular to contact surfaces of the opposing jaw members. The flow of electrical current causes the living tissue to coagulate, which, in turn, causes the impedance of the tissue to rise in the region between the contact surfaces of the opposing jaw members. Because uncoagulated tissue in the region generally between the periphery of the respective contact surfaces has a lower impedance compared to the coagulated tissue, the uncoagulated tissue provides a more favorable path for the electrical current to continue flowing through the tissue. As a result, the living tissue between the periphery of the opposing contact surfaces now starts to coagulate, causing what is referred to herein as a “thermal margin” to spread laterally and extend into the tissue beyond the region between the respective jaw members.
The conventional electrosurgical forceps described above have several drawbacks. For example, the thermal margin resulting from use of such conventional electrosurgical forceps can cause the impedance of the tissue near or touching the contact surfaces of the opposing jaw members to increase to a level where the flow of electrical current through the tissue is significantly reduced, possibly preventing further coagulation of the tissue. Moreover, as the thermal margin spreads laterally and extends into the living tissue, tissue structures adjacent the region between the opposing jaw members may potentially become damaged, thereby limiting the overall utility of the conventional electrosurgical forceps.
In addition, because the electrodes formed by the opposing jaw members of such conventional electrosurgical forceps are charged to different electrical potentials, an electrical short circuit can result if the contact surfaces of the opposing jaw members inadvertently touch one another during use. This can sometimes occur if the opposing jaw members grasp very thin tissue, or clamp onto the living tissue with excessive force. Such electrical shorting of the opposing contact surfaces can stop any electrical current from flowing through the living tissue, possibly preventing the conventional electrosurgical forceps from providing hemostatis at a time when it may be most needed.
It would therefore be desirable to have electrosurgical forceps that avoid at least some of the drawbacks of the conventional electrosurgical forceps described above.